OK, back to the beast again. On the road, temperature is just slightly = above mid-range, where it has always been. When stopped with engine = idling, the temp slowly increases. If I set for more than a few = minutes, it approaches max full scale. When I drive off, it comes back = to normal.
Another symptom - that may or may not be normal or related - is when I = start up cold, it takes a good 10 minutes to come up to temperature. = Other car takes about 2 minutes.
R/R fan clutch -- no change.
Sounds like the thermostatic radiator valve that opens as the engine warms up is jammed shut. When the car is running down the road, there's enough air flow to keep the engine cool.
Or, the valve's "opening" temperature has become too high, and it won't open up until the idling engine gets really hot.
above mid-range, where it has always been. =A0 When stopped with engine id= ling, the temp slowly increases. =A0 If I set for more than a few minutes, = it approaches max full scale. =A0 When I drive off, it comes back to normal= .
art up cold, it takes a good 10 minutes to come up to temperature. =A0Other= car takes about 2 minutes.
Do you see the fan spinning?
What happens if you turn the heat on while you idle?
That was my first thought as well, but modern 'stats are usually designed to fail 'safe' i.e. open. How about an air lock? Some engines are very fussy about getting the head full of water. I used to own a 5 cylinder Passat, and you had to jack one side of the vehicle up really high to get all of the air out, otherwise, it did just the sort of crap that you are describing ...
Arfa
Are you sure the fan clutch is good? If you rev the engine to 3000 RPM or so, the fan should really roar, especially when the engine is hot. Since the problem occurs at idle, maybe you can spray a spot of paint on one fan blade, so you can gauge the fan RPM. The fan clutches are supposed to couple well at low RPM, and when hot, and less well when cool and at higher RPM. I'm assuming a fluid clutch.
Jon
First of all was the coolant filled using the proper procedure ? If not the= re could be an air pocket.=20
Second a Tstat cannot be designed to failsafe open, and EVERY time that eng= ine overheats the stat could go bad. Luckily they are cheap.
Third the radiator could be clogged at the bottom.=20
To check it out, first of all run it with the radiator cap off, I DO NOT me= an the reservoir, I mean the radiator itself. Some actully do not have one = but that vehicle should. Fill the water and rev the gas using the throttle.= If the water comes up you need a head gasket at least. If the water does n= othing try a water pump, I have actually seen them with broken impellors in= ternally.=20
If the water does suck down, regardless of if the Tstat is open or not, sus= pect the radiator itself. It could be half clogged. You have no way of know= ing except maybe to run the vehicle until it gets really hot and compare th= e temperature of the top and bottom of the radiator. The top will always be= hotter but, then you have to guage how much. Let's put it this way, if it = is about to boil over and you can put your hand on the bottom of it, it's c= logged. However on that vehicle I dount you can do that.=20
Got one of those heat detecting gun jobbies ?=20
Anyway, unless you have an EXTREMELY wierd engine management problem or a h= ead or head gasket leakage, I have the solution. I have done it a few times= because you don't f*ck around with two things - cooling and oil.=20
If I verified that there was no head/gasket problems I would get a recored = radiator, a new water pump, thermostat as well as hoses. And a belt for the= hell of it. Put it all in at once and then follow the proper filling proce= dure.=20
First of all in my cars, even though it is not recommended, fukum - pure an= tifreeze. You put it in and then start it. You run it as it sucks it down. = THIS TAKES TIME. you keep on filling it and filling it until it starts comi= ng out, BUT before you call it full you MUST see the coolant circulationg. = You will see it spurting out the tubes inside the radiator.=20
However if it doesn't have an actual radiator cap, which is not that unusua= l anymore, there will be an air bleed, most likely at the top of the Tstat = housing, but not always. A 1997 vehicle should be as I described, and a For= d will be using a conventional cooling system, not a polypropylene or oil b= ased system so what I said should apply.
Before investing all that money though, run a compression check just to mak= e DAMN SURE you don't have a headgasket problem. They are more common than = people think. If you DO need headgaskets, get Felpro Printoseals, the metal= kind.=20
It will run better than ever, and I am not kidding. The metal gasket is usu= ally thinner which will raise the theoretical compression ratio. If it's a = V6 (likely) with hydraulic lifters there will be zero compression once you = install them. Pull the ECM fuse to turn off the injectors and let it crank = under that no load condition until it starts sounding like a car engine rat= her than an electric motor. Throw the fuse back in and start it but DO NOT = touch the accelerator. Let it idle however rough, even if it stumbles and s= talls, DO NOT rev the engine up.=20
After that you wil not only have a nice cool running engine, but more horse= power than you were used to. Believe me I have done it. Of course you only = gain that if the new gaskets are thinner than the originals. The Printoseal= s usually are, they are the equivalent of shaving the heads.
J
mid-range, where it has always been. When stopped with engine idling, the temp slowly increases. If I set for more than a few minutes, it approaches max full scale. When I drive off, it comes back to normal.
cold, it takes a good 10 minutes to come up to temperature. Other car takes about 2 minutes.
First, analyse the problem. It's a Ford (Found On Road Dead).
OK, lets go a little deeper. The engine temperature is fine at road (highway?) speeds when the engine is working hard. The temperature rises when the engine idles. Air flow over the engine will not keep it cool, that's why they have radiators.
I have never encountered an air lock problem, but will admit that others may have more experience.
This does not sound like a thermostat problem. With a faulty thermostat I would expect the engine to run at an elevated temperature while pulling a load, and cool off when idling. A problem I HAVE encountered is a defective radiator core - the fins had broken free of the tubes. Again, it would run cool at idle and overheat under load.
The symptoms sound like the fan is not moving enough air - at driving speeds sufficient air is forced through the radiator to dissipate the heat, at idle the air isn't moving fast enough. The three possible causes are a slipping fan belt, a defective fan clutch (which you have already replaced), or a fan in backwards. If the fan blades are curved there is only one 'right' way for it to be installed. A friend made that mistake once - and got the 'Mr. Badwrench' award.
PlainBill
Why would you do that? It's not nearly as effective at cooling as the recommended water-antifreeze mixture (it gets worse as the glycol concentration increases). It also freezes at a relatively high temperature (10°F/-12°C)!
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
snipped-for-privacy@yawhoo.com wrote in news: snipped-for-privacy@4ax.com:
that's a bad thermostat. they often are designed to fail "open". then your temp climbs when not moving,and drops when you are moving.
For a '97 anything,it's about time the TS was replaced. Make sure you get an OEM replacement,because the generics may not be the proper temp rating,despite what their little catalog says.Had that probem with my 94 Integra. their book said 180 degF,MY TS was a 194 degF.
-- Jim Yanik jyanik at localnet dot com
They cannot be designed to fail open.
J
That is an interesting point. I clearly recall thermostats that either failed to close completely or opened at too low a temperature. On the other hand, the usual thermostat design utilizes a wax pellet that forces the valve open. I can't see any way to design that to fail open.
Still, that is clearly not the problem in this case. As described, the engine runs at near normal temperature while the van is in motion, but overheats when stopped. I have seen that problem once - my Father-in-law had disconnected the electric radiator fan on his Audi because he didn't like the fact it ran after the engine was turned off. The engine would stay at normal temperatures while it was in motion, but overheat when standing - for example at a traffic light.
PlainBill
above mid-range, where it has always been. When stopped with engine = idling, the temp slowly increases. If I set for more than a few = minutes, it approaches max full scale. When I drive off, it comes back = to normal.
start up cold, it takes a good 10 minutes to come up to temperature. = Other car takes about 2 minutes.
Sounds like an inadequate radiator or radiator fan to me. Consider upgrading either of both.
?-)
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